GSA GEOLOGIC TIME SCALE
MESOZOIC
OLIGOCENE
C9
11
13
19
C18
20
C20
45
21
50
C21
22 C22
23
140
28.1
150
RUPELIAN
37.8
BARTONIAN
41.2
LUTETIAN
180
190
47.8
YPRESIAN
C23
26
C26
60
27
C27
28 C28
65
29
C29
30 C30
PALEOCENE
C25
300
ALBIAN
113
320
APTIAN
EARLY
BARREMIAN
HAUTERIVIAN
126
131
134
139
LATE
MIDDLE
KIMMERIDGIAN
OXFORDIAN
CALLOVIAN
BATHONIAN
BAJOCIAN
AALENIAN
152
380
157
164
166
168
170
174
400
56.0
220
THANETIAN
SELANDIAN
59.2
61.6
230
240
DANIAN
66.0
250
PERMIAN
Cisuralian
PLIENSBACHIAN
420
440
191
SINEMURIAN
HETTANGIAN
199
201
460
209
480
LATE
CHRON.
ERA
PERIOD
228
LADINIAN
ANISIAN
EARLY
OLENEKIAN
INDUAN
MIDDLE
MOSCOVIAN
EARLY
BASHKIRIAN
LATE
SERPUKHOVIAN
MIDDLE
VISEAN
EARLY
TOURNAISIAN
LATE
237
520
241
247
250
252
540
1250
315
323
1500
331
347
MIDDLE
1750
359
2000
372
GIVETIAN
EIFELIAN
383
388
393
PRIDOLI
LUDLOW
WENLOCK
LLANDOVERY
LATE
MIDDLE
EARLY
Epoch 3
Epoch 2
TERRENEUVIAN
LUDFORDIAN
GORSTIAN
HOMERIAN
SHEINWOODIAN
TELYCHIAN
AERONIAN
RHUDDANIAN
HIRNANTIAN
KATIAN
SANDBIAN
DARRIWILIAN
DAPINGIAN
FLOIAN
TREMADOCIAN
AGE 10
JIANGSHANIAN
PAIBIAN
GUZHANGIAN
DRUMIAN
AGE 5
AGE 4
AGE 3
AGE 2
408
411
419
423
426
427
430
433
439
441
444
445
453
458
467
470
635
CRYOGENIAN
850
1000
1200
MESOPROTEROZOIC
ECTASIAN
1400
CALYMMIAN
1600
STATHERIAN
1800
OROSIRIAN
PALEOPROTEROZOIC
2050
RHYACIAN
2250
2300
SIDERIAN
2500
2500
NEOARCHEAN
2750
2800
3000
3250
478
485
490
494
497
501
505
509
514
541
STENIAN
EMSIAN
PRAGIAN
BDY.
AGES
(Ma)
TONIAN
1000
290
296
299
304
307
NEOPROTEROZOIC
750
FRASNIAN
FURONGIAN
CARNIAN
260
265
269
272
279
ARTINSKIAN
SAKMARIAN
ASSELIAN
GZHELIAN
KASIMOVIAN
EDIACARAN
252
254
FAMENNIAN
NORIAN
500
MIDDLE
CHANGHSINGIAN
WUCHIAPINGIAN
CAPITANIAN
WORDIAN
ROADIAN
KUNGURIAN
LOCHKOVIAN
183
EARLY
LATE
EARLY
TOARCIAN
200
210
Guadalupian
360
145
TITHONIAN
M22
340
RHAETIAN
C24
25
280
93.9
100
BERRIASIAN
160
170
83.6
86.3
89.8
CENOMANIAN
VALANGINIAN
M25
24
55
TURONIAN
M12
M14
M16
M18
M20
M29
PRIABONIAN
C17
C19
130
M0r
M1
M3
M5
SANTONIAN
CONIACIAN
M10
33.9
EOCENE
18
120
CHATTIAN
C13
15 C15
16 C16
17
40
C12
PALEOGENE
35
C11
HIST
BURDIGALIAN
23.0
10 C10
12
110
AQUITANIAN
7 C7
7A C7A
8 C8
34 C34
EON
PROTEROZOIC
16.0
6C C6C
30
100
LANGHIAN
20.4
6B C6B
9
13.8
C6
6A C6A
25
11.6
AGE
(Ma)
3500
ARCHEAN
20
5E
6
C5E
SERRAVALLIAN
90
CAMPANIAN
LATE
PENNSYLVANIAN
5B C5B
5C C5C
5D C5D
TORTONIAN
260
MISSISSIPPIAN
C5A
33
C33
Lopingian
72.1
CARBONIFEROUS
15
C5
MAASTRICHTIAN
32 C32
80
AGE
PRECAMBRIAN
PICKS
(Ma)
66.0
30 C30
31 C31
7.2
AGE
PERIOD EPOCH
(Ma)
DEVONIAN
5A
C4A
MIOCENE
5
NEOGENE
4A
10
C4
5.3
70
AGE
PALEOZOIC
PICKS
(Ma)
ORDOVICIAN SILURIAN
MESSINIAN
3A C3A
4
PIACENZIAN
ZANCLEAN
0.01
1.8
2.6
3.6
CRETACEOUS
5
PLIOCENE
C3
CALABRIAN
GELASIAN
PERIOD EPOCH
JURASSIC
HOLOCENE
QUATERNARY PLEISTOCENE*
2A C2A
3
AGE
MAGNETIC
POLARITY
TRIASSIC
C1
C2
EPOCH
AGE
(Ma)
RAPID POLARITY CHANGES
1
2
PERIOD
PICKS
(Ma)
ANOM.
CHRON.
HIST.
ANOM.
MAGNETIC
POLARITY
CAMBRIAN
CENOZOIC
AGE
(Ma)
v. 4.0
MESOARCHEAN
3200
PALEOARCHEAN
3600
3750
EOARCHEAN
521
529
FORTUNIAN
541
4000
4000
HADEAN
*The Pleistocene is divided into four ages, but only two are shown here. What is shown as Calabrian is actually three ages—Calabrian from 1.8 to 0.78 Ma, Middle from 0.78 to 0.13 Ma, and Late from 0.13 to 0.01 Ma.
Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E., compilers, 2012, Geologic Time Scale v. 4.0: Geological Society of America, doi: 10.1130/2012.CTS004R3C. ©2012 The Geological Society of America.
The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon. Names of units and age boundaries follow the Gradstein et al. (2012) and Cohen et al. (2012) compilations. Age estimates and picks of boundaries
are rounded to the nearest whole number (1 Ma) for the pre-Cenomanian, and rounded to one decimal place (100 ka) for the Cenomanian to Pleistocene interval. The numbered epochs and ages of the Cambrian are provisional.
REFERENCES CITED Cohen, K.M., Finney, S., and Gibbard, P.L., 2012, International Chronostratigraphic Chart: International Commission on Stratigraphy, www.stratigraphy.org (last accessed May 2012). (Chart reproduced
for the 34th International Geological Congress, Brisbane, Australia, 5–10 August 2012.)
Gradstein, F.M, Ogg, J.G., Schmitz, M.D., et al., 2012, The Geologic Time Scale 2012: Boston, USA, Elsevier, DOI: 10.1016/B978-0-444-59425-9.00004-4.